It is generally known that for any given selected number of dimples on a golf ball, it is desirable that the area of the surface of the golf ball covered by the dimples be a maximum in order to provide the best flight characteristics for a golf ball. In British Patent Provisional Specification Serial No. 377,354, filed May 22, 1931, in the name of John Vernon Pugh, there is disclosed the fact that by the use of an icosahedral lattice for defining dimple patterns on a golf ball it is possible to make a geometrically symmetrical ball. This icosahedral lattice is developed by the known division of a sphere or spherical surface into like areas determined by an inscribed regular polyhedron such as an icosahedron. The Pugh specification specifically details the means of plotting the icosahedron on the surface of the golf ball and, accordingly, will not be dealt with in detail here. Thus, with a selected number and size of dimples placed in this icosahedral pattern, the area of the surface of the ball covered by the dimples is fixed.
A problem arises with the Pugh icosahedron golf ball in that there is no equatorial line on the ball which does not pass through some of the dimples on the ball. Since golf balls are molded and manufactured by using two hemispherical half molds normally having straight edges, the ball as it comes from the mold has a flash line about the equatorial line created by the two hemispheres of the mold. Such molding results in a clear flash line. Even if the ball could be molded with dimples on the flash line, the ball could not be properly cleaned and finished in any efficient manner since the flash could not be cleaned from the bottom of the dimple without individual treatment of each dimple.
The Pugh ball is geometrically symmetrical. Any changes in dimple location which affect the aerodynamic symmetry under U.S.G.A. standards will render the ball illegal for sanctioned play. Many proposals have been made and balls have been constructed with a modification of the Pugh icosahedral pattern so as to provide an equatorial line which is free of dimples. Again, it is emphasized that any such modification must be aerodynamically symmetrical.
Other dimple patterns have been proposed which use various geometrical arrangements. U.S. Pat. No. 4,932,644 to Pocklington et al discloses a golf ball having a dimple configuration arranged in these different patterns comprising a pentagon at each pole, five trapezoid formations in each hemisphere, and five triangular formations in each hemisphere.
U.S. Pat. No. 5,018,741 to Stiefel et al discloses a modified icosahedral dimple pattern having a total of 422 dimples using dimples having three different diameters.
U.S. Pat. No. 5,009,427 to Stiefel et al discloses a dimple pattern using a first set of five triangles and a second set of five triangles using dimples having two different diameters, the pattern having 402 dimples. The present invention is a modification of that dimple pattern using three different dimple diameters for providing different flight and distance parameters.
U.S.G.A. rules of golf require that the ball shall be designed and manufactured to perform in general as if it were aerodynamically symmetrical. A golf ball which is dimpled in some manner may be geometrically symmetrical and not aerodynamically symmetrical. A perfect example of a golf ball which is both geometrically symmetrical and aerodynamically symmetrical is a smooth sphere. As is well known, this ball is not capable of providing the necessary performance required in present-day golf. To conform, all balls must be aerodynamically symmetrical. This symmetry is determined by actual tests of the ball as it is being struck by a machine which belongs to the U.S.G.A.
It has been found that it is desirable to cover as much of the surface as possible with the dimples. While a great deal of the surface may be covered by making the dimples quite small, it has been found that this imparts some undesirable characteristics to the ball. At the same time, when larger diameter dimples are used and all the dimples are the same size, they should be arranged so as to cover the maximum surface area of the ball.
Accordingly, it is an object of the present invention to provide a dimpled golf ball having 402 dimples wherein a substantially maximum area of the surface is covered by dimples.
It is yet another object of the present invention to provide a dimpled golf ball wherein the dimples are formed in a pattern which includes a plurality of triangles.
These and other objects of the invention will become apparent from the following description taken together with the drawings.